Deformation of NHL3.5 and CL90/PC hybrid mortars

The time-dependent deformation of an NHL 3.5 natural hydraulic lime mortar, a 1:6 Portland cement mortar, two Portland cement/CL90 hybrid mortars and a CL90 lime paste, through creep and drying shrinkage under load, has been investigated. An apparatus was constructed to measure the dimensional changes of eight individual samples simultaneously. A reversible relationship between changes in specimen dimension and relative humidity has been established. The influence of load on deformation rate was found to be most significant during the first two weeks of monitoring with little effect thereafter. The rate of deformation during the first 2 weeks of sample monitoring was greatest for mortars containing a high proportion of calcium hydroxide. A linear relationship was found between strain rate and calcium hydroxide content.